1. Field of the Invention
The present invention relates to an active matrix driven or passive matrix driven electro-optical apparatus such as a liquid crystal apparatus based on thin-film transistor driving or thin-film diode driving, a manufacturing method thereof, and an electronic device using the same.
2. Description of Related Art
A liquid. crystal apparatus typically includes an electro-optical apparatus, a pair of alignment films that are rubbed in prescribed directions and provided on a pixel electrode and an opposing electrode between a pair of substrates, and an electro-optical material such as liquid crystal held between the alignment films. An electric field is applied to the electro-optical material from both electrodes. As a result, the alignment condition of the electro-optical material changes and a display is provided within an image display area.
Therefore, if a convex or concave portion caused by a difference in the total film thickness between an area comprising wiring lines (such as data lines, scanning lines and capacitor lines), driving circuits for driving pixels and the like such as thin-film transistor driving circuits (TFT) and thin-film diode elements (TFD) is left as it is up to a face (alignment film) in contact with the electro-optical material, then, defective alignment (disclination) may occur in the electro-optical material in response to the extent of convex or concave, which may lead to deterioration of the image for each pixel. More specifically, when an alignment film having an aperture area formed on the convex or concave face is rubbed, variations may occur in the alignment regulating ability on the alignment film surface in response to the extent of convex or concave. This may cause defective alignment of the electro-optical material and change the display contrast. Upon defective alignment of the electro-optical material for a normally white mode in which non-application of voltage onto the electro-optical material results in white display, a white dropout may occur at the position of defective alignment, which leads to a decrease in contrast which in turn leads to a decrease in fineness. In order to uniformly rub the alignment film over the entire substrate, a prescribed constant distance is maintained between the alignment films. To avoid this inconvenience, it is very important to flatten a pixel portion positioned within the image display area.
On the other hand, an electro-optical material may be sealed in a space surrounded by a sealing material between both substrates having wiring lines and driving circuits to form an electro-optical material layer. The sealing material may be an adhesive comprising a photosetting resin or a thermosetting resin for bonding both substrates around them. Particularly in a small-capacity electro-optical apparatus, the gap between the substrates may be controlled using a sealing material mixed with a bead-shaped or fiber-shaped gap material having an outside diameter of several xcexcm. In the sealed area (i.e., area bonded by the sealing material), outgoing wire lines of the scanning and data lines are arranged from the image display area to the peripheral areas. This produces a step depending upon the presence or absence of the connecting lines. Such a step makes it difficult to gap control using the gap filler and stress concentration by the gap filler may cause breakage of lines or cause a short circuit. It is therefore very important to flatter the sealed area.
In order to flatten the above-described pixel portion for one or a plurality of interlayer insulating films provided to insulate individual thin films composing a thin-film transistor or individual thin films composing various wiring lines, the thickness of a non-aperture area of each pixel may be smaller than the thickness of an aperture area thereof. Or, it may be necessary to flatten the upper surface of the interlayer insulating film closest to the electro-optical material using a CMP (Chemical Mechanial Polishing) operation or to form a SOG (Spin On Glass) film using a spin coating operation.
Also for flattening the sealed area as described above, the thickness of the portion having connecting lines formed thereon may be smaller than the thickness having no connecting line thereon. Or, the upper surface of the interlayer insulating film closest to the sealed area may be flattered by forming an SOG using a CMP operation or spin coating.
At all events, therefore, there are posed problems of more complicated manufacturing steps, a lower yield and a high cost.
In order to prevent flicker or a cross-talk even with a low duty ratio upon supplying image signals to each pixel electrode in an electro-optical apparatus of this type, a storage capacitor may be provided for imparting a prescribed capacity to each pixel electrode. The total film thickness in the non-aperture area may be increased by an amount corresponding to the storage capacitor electrode and the capacitor lines composing the same. This may result in an increase in step in the pixel section. When such a storage capacitor is incorporated in an area under the data lines or along the scanning lines, thickness in this portion may increase causing production of a large step. For example, when incorporating a storage capacitor in the area under the data lines, the thickness may increase compared to that of the pixel section not having them by an amount corresponding to the thickness of the storage capacitor (i.e., total thickness of the first storage capacitor electrode, the insulating film and the second storage capacitor electrode) and the data line thickness. This may result in a step of about 10,000 xc3x85. Thus, flattening applied for offsetting the step in the image display area may be difficult and expensive.
In an electro-optical apparatus having each pixel provided with a thin-film transistor, a light shielding film may be provided under the thin-film transistor (on the TFT array substrate side) with a view to prevent optical leakage caused by a feedback light from the back of the projected light having transmitted through the electro-optical apparatus incoming into a channel area of the thin-film transistor particularly in a use such as a projector. Thus, the total thickness in the non-aperture area having a TFT formed thereon becomes larger by an amount corresponding to the light shielding film. This results in a larger step. In this case, the flatten applied for offsetting the step in the image display area may be difficult and expensive.
The present invention may provide an electro-optical apparatus which can reduce the step caused by the presence of various wiring lines and elements in the image display area by using a relatively simple configuration, a manufacturing method thereof, and an electronic device using the same.
An electro-optical apparatus may be provided to reduce the step caused by the presence of various wiring lines in the sealed area by the use of a relatively simple configuration, a manufacturing method thereof, and an electronic device using the same.
An object of the present invention may be to provide an electro-optical apparatus that permits efficient flattening of the pixel section by the utilization of the configuration in which a light shielding film is provided under the TFT and features of the manufacturing steps, a manufacturing method thereof, and an electronic device using the same.
An object of the invention may be to provide an electro-optical apparatus having a large storage capacitor in which defective alignment of liquid crystal may be reduced as far as possible. A manufacturing method and a electronic device using the same may also be provided.
An object of the present invention may be to provide an electro-optical apparatus which permits reduction of defective wiring under the sealed area and accurate control of the gap between substrates. A manufacturing method and an electronic device using the same may also be provided.
An electro-optical apparatus may include a first substrate having a first face provided with a concave recess and a second face. A second substrate may be arranged opposite to the first face. An electro-optical material may be held between the first face and the second substrate. A plurality of pixel electrodes may be formed on the first face and a plurality of wiring lines may be formed on the first face so as to be at least partially positioned on the concave recess and connected to the pixel electrodes.
In one of the substrates (first substrate), the area opposite to a plurality of wiring lines on the side facing the electro-optical material (first face side) may be at least partially a concave recess. The surface of the uppermost layer (alignment film) located above wiring lines (such as data lines scanning lines and capacitor lines) may be flattened toward the aperture areas of pixels (i.e., the area where pixels electrode are formed) in response to the depth of recess in the area having the concave recess formed therein. For example, when an area where the lamination forming the wiring lines has the largest thickness because of overlapping of various wiring lines is formed into a concave shape to a depth equal to the total layer thickness thereof, this area may be completely flattened. Or, when all the non-aperture areas opposite to the electro-optical material except for the pixel electrodes (with various wiring lines formed thereon) are formed into concave recesses, the aperture area and the non-aperture areas of the pixels are flattened. Similarly when the substrate area opposite to the connecting lines in the sealed area is formed into a concave recess, it is possible to reduce a step caused by the presence of connecting lines in the sealed area, and-thus to flatten the sealed area.
The electro-optical apparatus may be formed by forming a concave recess on the substrate in an initial stage of manufacture, and the subsequent steps of including the sputtering step, the photolithographic step and the etching step may be carried out in substantially the same or similar manner as in the conventional art, thus providing very favorable advantages. In addition, it is not necessary to use a larger thickness for a portion of the interlayer insulating film and a smaller thickness for the other portion thereof as described above. There is therefore no risk of occurrence of cracks at thicker portions of the interlayer insulating film or back channel at thinner portions thereof. This leads to a remarkably improved degree of freedom in design, makes it unnecessary to conduct difficult manufacturing steps or additional steps, and does not lead to an increase in cost.
In an electro-optical apparatus including active matrix driving type, passive matrix driving type and segment driving type, a step in the pixel section can be reduced by the use of a relatively simple configuration. It is therefore possible to efficiently reduce defective alignment of the electro-optical material by an inappropriate rubbing processing due to a step, or directly caused by a deviated distance between the substrates due to a step. Further, because a step in the sealed area can be reduced by the use of a relatively simple configuration, it is also possible to efficiently perform gap control between the substrates and prevent deterioration of connecting lines.
The electro-optical apparatus according to one aspect of the present invention includes a first substrate having a first face and a second face and provided with a concave recess formed on the first face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrate, a plurality of pixel electrodes formed on the first face, and a plurality of wiring lines formed on the first face to be at least partially positioned on the concave recess, respectively, and connected to the pixel electrodes.
According to the invention, portions opposite to the TFT, the data lines and the scanning lines may be formed into concave recesses when viewed from the second substrate side. As compared with the conventional case in which the interlayer insulating film is formed into a flat shape, and then the TFT and other components are formed thereon, therefore, the difference in total thickness between an area having the TFT and other components formed thereon and an area not having these components, depending upon the depth of the concave recess, is reduced. This promotes flattening in the pixel section. For example, by setting a depth of the concave recess so as to bring the difference in total thickness substantially to zero, a subsequent flattening step can be omitted. Or, by setting a depth of the concave recess so as to reduce the difference in the total layer thickness, it is possible to alleviate the burden of the subsequent flattening step. More specifically, conventional steps including the coating step of a flattened film by spin coating and the forming step of a flattened insulating film can be omitted or simplified.
The electro-optical apparatus according to one aspect of the present invention includes a first substrate having a first face and a second face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrates, a plurality of pixel electrodes formed on the first face, and an interlayer insulating film formed on the first face so as to have a concave recess directed toward the electro-optical material. A plurality of wiring lines may be formed on the first face so as to be at least partially positioned on the concave recess and connected to the pixel electrodes. A plurality of capacitor lines may be formed on the first face so as to be at least partially positioned under the wiring lines on the concave recess for imparting a capacity to each of the pixel electrodes.
Because the incident light does not transmit, the space under wiring lines (such as data lines) unavailable as an aperture area can be effectively utilized as a space for imparting a capacitor to the pixel electrodes.
Further, according to the invention, an area of the interlayer insulating film opposite to the capacitor lines may be formed into a concave recess as compared with other areas. For example, the surface of the pixel electrode located above the data lines may be flattened by this recess. In the conventional art, defective alignment of a liquid crystal may have been caused by inappropriate rub processing due to a step, or directly caused by a deviated distance between substrates due to a step, most easily at the portion of the aperture area along the data lines. However, defective alignment at this portion can be minimized through flattening.
The electro-optical apparatus according to one aspect of the present invention may include a first substrate having a first face and a second face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrate and a plurality of pixels electrodes formed on the first face. A plurality of wiring lines may be formed on the first face and connected to the pixel electrodes. A sealing material may be mixed with a gap filler for bonding the first face and the second substrate together. A plurality of connecting lines may be formed in an area where the sealing material is formed on the first face and extends from the wiring lines, respectively. An interlayer insulating film may be formed on the first face so as to have a concave recess between the first face and the connecting lines.
The first and the second substrates may be bonded to each other, and the gap between the substrates may be filled with a gap filler mixed with a sealing material. The apparatus of the invention in therefore embodied in a liquid crystal apparatus of the active matrix driving type such as TFT (thin-film transistor) driving or TFD (thin-film diode) driving, or a liquid crystal apparatus of the passive matrix driving type, provided with liquid crystal having a prescribed thickness, and being matrix-driven by the data lines and the scanning lines. In the interlayer insulating film, the portion opposite to the connecting lines in the sealed area may be formed into a concave recess. Therefore, the height of a projection caused by the thickness of the connecting lines formed on the surface of the uppermost layer (hereinafter referred to as the xe2x80x9csealed area surfacexe2x80x9d) such as an interlayer insulating film in contact with the sealing material in the sealed area on the substrate side having the data lines and the scanning lines formed thereon is reduced in response to the depth of the concave recess. That is, the surface of the sealed area may be flattened. As a result, this stress may be uniformly dispersed over the surface on the flattened sealed area via the gap filler mixed with the sealing material. This may reduce the possibility of breakage of connecting lines or short circuits. By reducing the difference in height on the surface of the sealed area, if not substantially to zero, but only slightly, the possibility of breakage of connecting lines or short circuit is reduced at least slightly under a similar effect.
Further, the surface of the uppermost layer of the alignment film or the like in contact with the liquid crystal in each pixel area on the substrate surface having data lines or scanning lines formed thereon (hereinafter referred to as the xe2x80x9cpixel area surfacexe2x80x9d) has almost the same height as that of a portion of the sealed area surface not located on the connecting lines. The difference in height between the pixel area surface and the sealed area surface is therefore reduced by flattening the sealed area surface. As a result, a gap filler may not be needed having a smaller diameter than the gap between substrates by about 1 xcexcm as in the conventional art. It is possible to use a gap filler having a diameter of the same order as that of the gap between the substrates. This permits expectation of a remarkable effect when reducing the gap between the substrates to prevent defective alignment of the liquid crystal caused by finer pixels.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of forming a resist pattern corresponding to a concave recess by photolithography on a flat substrate serving as the first substrate, a step of forming the concave recess through etching for a prescribed period of time via the resist pattern and a step of forming a plurality of pixel electrodes and a plurality of wiring lines in a prescribed sequence on the first substrate including the concave recess.
A resist pattern corresponding to the concave recess may be formed by photolithography on the flat substrate serving as the first substrate. Then, etching may be carried out for a prescribed period of time via this resist pattern to form a concave portion. By controlling the etching time, it may be possible to control the depth of the concave recess and the film thickness. When using dry etching, an aperture having substantially the designed exposure size can be provided. Then, a plurality of pixel electrodes and a plurality of wiring lines may be formed in a prescribed sequence on the substrate containing the concave recess. It is therefore possible to manufacture the electro-optical apparatus of the invention relatively easily. Particularly, by forming a concave recess on the substrate in an initial stage of manufacture, the electro-optical apparatus of the invention may be favorably manufactured by only executing the subsequent steps in substantially or in the same manner as in the conventional art.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of forming a light shielding film in a prescribed area on the first substrate, a step of depositing an interlayer insulating film on the first substrate and the light shielding film, a step of forming a resist pattern corresponding to a concave recess on the insulating film by photolithography and a step of forming the concave recess by dry etching for a prescribed period of time via the resist pattern.
A light shielding film may be formed in a prescribed area on a first substrate, and an insulating film may be deposited on the first substrate and the light shielding film. Then, a resist pattern corresponding to a concave recess may be formed by photolithography on the insulating film, and then the concave recess is formed through dry etching for a prescribed period of time via the resist pattern. It is therefore possible to control the depth of the concave recess and the film thickness through control of the dry etching time.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of-forming a light shielding film in a prescribed area on the first substrate, a step of depositing a first insulating film on the first substrate and the light shielding film, a step of forming a resist pattern corresponding to a concave recess on the first insulating film by photolithography, a step of removing the first insulating film corresponding to the concave recess through etching via the resist pattern and a step of depositing a second insulating film on the first substrate and the first insulating film.
A light shielding film may be formed in a prescribed area on a first substrate, and a first insulating film may be deposited on the first substrate and the light shielding film. Then, a resist pattern corresponding to a concave recess may be formed by photolithography on the first insulating film, and then, etching may be performed via the resist pattern to remove the first insulating film corresponding to the concave recess. Then, a second insulating film is deposited on the first substrate and the first insulating film. As a result, certain and highly accurately control of the thickness of the first interlayer insulating film at the concave recess portion may be accomplished through control of thickness of the second insulating film.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of forming a light shielding film in a prescribed area on the first substance, a step of forming a first interlayer insulating film on the first substrate and the light shielding film so that concave recesses are formed on the portion opposite to a thin-film transistor and a portion corresponding to the position of connection and a step of forming the thin-film transistor on the first interlayer insulating film. The method may further include a step of aperturing the second and first interlayer insulating films to reach the light shielding film at the position for connection as contact holes for connecting the light shielding film and the wiring lines from the contact potential source, and at the same time, aperturing the second and first insulating films to reach a semiconductor layer at a position opposite to a source or drain area of the semiconductor layer forming the thin-film transistor, as contact holes for connecting the thin-film transistor and the data lines.
A light shielding film may be formed in a prescribed area on a first substrate, and a first interlayer insulating film may be formed on the first substrate and the light shielding film so that a portion corresponding to a TFT and a portion corresponding to a position for connection of the light shielding film and a constant potential source. Then, a TFT may be formed on the first interlayer insulating film, and a second interlayer insulating film may be formed on the TFT and the first interlayer insulating film. The second interlayer insulating film is provided for electric insulation of the TFT, the data lines, and the scanning lines. The second and the first interlayer insulating films may be apertured to reach the light shielding film as contact holes for connecting the light shielding film and the wiring lines from the constant potential source, and at the same time, the second insulating film may be apertured up to a semiconductor layer, as contact holes for connecting the TFT and the data lines. It is thus possible to aperture together these two kinds of contact holes.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of depositing an insulating film forming a single layer on the first substrate, a step of forming a resist pattern corresponding to a concave recess on the deposited insulating film by photolithography and a step of forming the concave recess through etching for a prescribed period of time via the resist pattern.
An insulating film to form the single layer on the first substrate may be deposited over the entire screen display area. Then, a resist pattern corresponding to a concave recess may be formed by photolithography on the deposited insulating film. Then, etching may be conducted for a prescribed period of time via the resist pattern to form a concave recess. The depth of the concave recess and the film thickness may be controlled based on the etching time. When dry etching is performed, an aperture having substantially a designed exposure size can be provided.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of depositing a first insulating film to form a multilayered portion on the first substrate, a step of forming a resist pattern corresponding to a concave recess on the deposited first insulating film by photolithography, a step of removing the first insulating film corresponding to the concave recess through etching via the resist pattern and a step of depositing a second insulating film to form the single-layered portion and a multilayered portion on the first insulating film and the area from which the first insulating film has been removed.
A first insulating film may be deposited over the entire screen display area to form a multilayered portion on a first substrate. Then, a resist pattern corresponding to a concave recess may be formed by photolithography on the deposited first insulating film. Etching may be carried out via the resist pattern to remove the first insulating film corresponding to the concave recess. Then, a second insulating film may be deposited on the first insulating film and the area from which the first insulating film has been removed. As a result, the thickness of the first interlayer insulating film in the concave recess portion may be controlled relatively easily through control of the thickness of the second insulating film. When dry etching is used in this etching step, an aperture having substantially a designed exposure size can be provided.
The manufacturing method of an electro-optical apparatus of one aspect of the present invention may include: a step of forming a light shielding film in a prescribed area of the first substrate, a step of forming a first interlayer insulating film on the first substrate and the light shielding film so that a portion corresponding to the position for connection becomes a concave portion, a step of forming a thin-film transistor on the first interlayer insulating film, a step of forming a second interlayer insulating film on the thin-film transistor and the first interlayer insulating film and a step of aperturing the second and first interlayer insulating films to reach the light shielding film at the position for connection as contact holes for connecting the light shielding film and the wiring lines from the contact potential source and at the same time aperturing the second and first insulating films to reach a semiconductor layer at a position opposite to a source or drain area of the semiconductor layer forming the thin-film transistor as contact holes for connecting the thin-film transistor and the data lines.
A light shielding film may be formed in a prescribed area on the first substrate, and a first interlayer insulating film may be formed on the first substrate and the light shielding film so that a portion corresponding to the position where the light shielding film and a constant potential source are connected together forms a concave recess. Then, a TFT may be formed on the first interlayer insulating film and a second interlayer insulating film may be formed on the TFT and the first interlayer insulating film. The second interlayer insulating film may be provided for electrical insulation of the TFT, the data lines, the scanning lines and the capacitor lines. The second and the first interlayer insulating films may be apertured to reach the light shielding film as contact holes for connection of the light shielding film and the wiring lines from the constant potential source. At the same time, the second interlayer insulating film may be apertured to reach a semiconductor layer as a contact hole for connection of the TFT and the data lines. It is therefore possible to aperture together two kinds of contact holes.
The electronic device using an electro-optical apparatus according to one aspect of the present invention may include: a first substrate having a first face and a second face and provided with a concave recess formed on the first face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrate, a plurality of pixel electrodes formed on the first face and a plurality of wiring lines formed on the first face so as to be at least partially positioned on the concave recess and the pixel electrodes.
The electronic device using an electro-optical apparatus according to one aspect of the present invention may include: a first substrate having a first face and a second face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrate, a plurality of pixel electrodes formed on the first face, an interlayer insulating film formed on the first face so as to have a concave recess facing the electro-optical material side and a plurality of wiring lines formed on the first face so as to be at least partially positioned on the concave recess and connected to the pixel electrodes.
The electronic device using an electro-optical apparatus according to one aspect of the present invention may include: a first substrate having a first face and a second face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrate, a plurality of pixel electrodes formed on the first face and an interlayer insulating film formed on the first face so as to have a concave recess facing the electro-optical material side. A plurality of wiring lines may be formed on the first face so as to be at least partially positioned on the concave recess and connected to the pixel electrodes. A plurality of capacitor lines may be formed on the first face so as to be at least partially positioned under the wiring lines on the concave recess for imparting a capacity to each of the pixel electrodes.
The electronic device using an electro-optical apparatus according to one aspect of the present invention may include: a first substrate having a first face and a second face, a second substrate arranged opposite to the first face, an electro-optical material held between the first face and the second substrate, a plurality of pixel electrodes formed on the first face and a plurality of wiring lines formed on the first face, and connected to the pixel electrodes. A sealing material mixed with a gap filler may also be provided for bonding together the first face and the second face. A plurality of connecting lines may be formed in an area where the sealing material is formed on the first face and extends from the wiring lines, respectively. An interlayer insulating film may be formed on the first face so as to have a concave recess between the first face and the connecting lines.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description taken in conjunction with the annexed drawings, which disclose preferred embodiments of the invention.